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Imaggeo on Mondays: The place where water runs through rocks

Imaggeo on Mondays: The place where water runs through rocks

Antelope Canyon, located in Arizona, USA, was formed by erosion of the Navajo Sandstone, primarily due to flash flooding and secondarily due to other sub-aerial processes (think of physical weathering processes such as freeze-thaw weathering exfoliation and salt crystallisation). Rainwater runs into the extensive basin above the slot canyon sections, picking up speed and sand as it rushes into the narrow passageways. Over time the passageways are eroded away, making the corridors deeper and smoothing hard edges in such a way as to form characteristic ‘flowing’ shapes in the rock.

The Navajo Sandstone was deposited in an aeolian (wind-blown) environment composed of large sand dunes: imagine a sea of sand, or an erg, as it is known scientifically, not dissimilar to the present Sarah desert landscape. The exact age of the Navajo Sandstone is controversial, with dated ages ranging from Triassic to early Jurassic, spanning a time period between 250 million years ago to approximately 175 million years ago. The difficulty in determining the exact age of the unit lies in its lack of age diagnostic fossils. The Navajo Sandstone is not alone in this quandary, dating is a common problem in aeolian sediments.

“The picture was taken during a three week Southwest USA road trip in summer 2012. One of the highlights was the visit to Antelope slot canyon, which is located on Navajo land east of Page, Arizona. The Navajo name for Upper Antelope Canyon is Tsé bighánílíní, which means the place where water runs through rocks,” explains Frederik Tack, an atmospheric scientist from the Belgian Institute for Space Aeronomy and author of today’s Imaggeo on Monday’s photograph.

The erosive processes which form the canyon are still ongoing. There is an elevated risk of flash floods, meaning the canyon can only be visited as part of guide tours.

“The canyon was actually quite crowded which made taking this picture challenging, especially as I wanted to capture the peace and solitude of the landscape,” describes Tack.

The effort was worth it: Waved rocks of Antelope slot canyon was one of the EGU’s 2015 Photo Contest finalists!

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: Sunset over the Labrador Sea

Ruby skies and calm waters are the backdrop for this week’s Imaggeo image – one of the ten finalist images in this year’s EGU Photo contest.

 Sunset over the Labrador Sea. Credit: Christof Pearce (distributed via  imaggeo.egu.eu)

Sunset over the Labrador Sea. Credit: Christof Pearce (distributed via imaggeo.egu.eu)

“I took the picture while on a scientific cruise in West Greenland in 2013,” explains Christof Pearce, a postdoctoral researcher at Stockholm University. “We spent most of the time inside the fjord systems around the Greenland capital, Nuuk, but this specific day we were outside on the shelf in the open Labrador Sea. The black dot on the horizon toward the right of the image is a massive iceberg floating in the distance.”

Pearce took part in a research cruise which aimed to obtain high-resolution marine sedimentary records, which would shed light on the geology and past climate of Greenland during the Holocene, the epoch which began 11,700 years ago and continues to the present day.

A total of 12 scientists and students took part in the Danish-Greenlandic-Canadian research cruise in the Godthåbsfjord complex and on the West Greenland shelf. By acquiring cores of the sediments at the bottom of the sea floor, the research team would be able to gather information such as sediment lithology, stable isotopes preserved in fossil foraminifera – sea fairing little creatures – which can yield information about past climates, amongst other data. One of the main research aims was to learn more about the rate at which the Greenland Ice Sheet melted during the Holocene and how this affected local climate conditions and the wider climate system.

“The picture was taken approximately 25 kilometres off the shore of west Greenland coast. In this region the water depth is ca. 500 meters,” describes Pearce. “At this location we deployed a so-called gravity corer and took a 6 meter long sediment core from the ocean floor. Based on radiocarbon measurements – by measuring how much carbon 14 is left in a sample, the age of the sampled units can be known – we now know that these 6 meters correspond to approximately 12000 years of sedimentation, and thus it captures a history of climate and oceanography from the last ice age all the way to present day.”

 

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: A voyage through scales – The Badlands National Park, South Dakota.

Imaggeo on Mondays: A voyage through scales – The Badlands National Park, South Dakota.

Layer upon layer of sand, clay and silt, cemented together over time to form the sedimentary units of the Badlands National Park in South Dakota, USA. The sediments, delivered by rivers and streams that criss-crossed the landscape, accumulated over a period of millions of years, ranging from the late Cretaceous Period (67 to 75 million years ago) throughout to the Oligocene Epoch (26 to 34 million years ago). Interbedded greyish volcanic ash layers, sandstones deposited in ancient river channels, red fossil soils (palaeosols), and black muds deposited in shallow prehistoric seas are testament to an ever changing landscape.

Fast forward to 500,000 years ago and the landscape was very different. The Cheyenne River diverted the flow of the ancient small streams and rivers down its own river bed, in a geomorphological process called capture. The destructive power of the river dominated over the deposition of sediment. The river cut through the layers of sediments and produced the stunning landscape preserved today.

“The picture was taken in 2009 as I made a road trip with my brother across the United States, from Chicago to San Francisco,” explains Iain Willis, author of today’s Imaggeo on Mondays photograph. “After a long day’s drive, we approached the edge of the Badlands in the late afternoon after turning off route 90. I took the picture of my brother after we’d taken a short walk across a couple of peaks. I didn’t think the picture would be so dramatic as it was actually pretty overcast but as I was setting up the sun was momentarily piercing through. I originally shot in colour but after seeing it in monochrome, it looked far more dramatic.”

Dramatic enough for the judges of this year’s Imaggeo Photo Competition to award Willis the prize for the image which best represented the theme of the 2015 General Assembly: A Voyage through Scales.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

General Assembly 2015 – Highlights

It’s been just over a month since the EGU General Assembly 2015 in Vienna. The conference this year was a great success with 4,870 oral, 8,489 poster, and 705 PICO presentations. There were 577 unique scientific sessions, complimented by an impressive 310 side events, making for an interesting and diverse programme.

The conference brought together 11,837 scientists from 108 countries, 23% of which were students. Keeping abreast of everything that was going on throughout the week was made easier due to the distribution of 15,000 copies of EGU Today, and as a result of a keen media presence and their reporting of the scientific sessions. Thousands of visits to the webstreams, as well as GeoLog, meant  those at the conference and those who couldn’t make it stayed tuned to the best of the conference! We thank all of you very much for your attendance and active contribution to the conference.

Why not watch this video of the best bits of the conference and highlights of a productive week?

The conference this year, as showcased in the highlights video, celebrate a theme: A voyage through scales. The theme was an invitation to contemplate the Earth’s extraordinary variability extending from milliseconds to its age, from microns to the size of the planet. The range of scales in space, in time – in space-time – is truly mindboggling. Their complexity challenges our ability to measure, to model, to comprehend. The range of scales were explored across four exhibition spots throughout the conference centre.

One of the exhibitions, ‘The scales in art‘, invited conference participants to participate in the dialogue between science and art. At the space, attendees watched the artistic interpretation of the theme developing over the week, with artist Eva Petrič.

We hope to see many of you at next year’s EGU General Assembly 2016 which takes place on: 17 – 22 April 2016, in Vienna, Austria.

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